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親子のコミュニケーションで理解しようとしています。免責事項：以下は、プロセス間通信を理解するためにクラスの私の教授によって提供されたサンプルコードです。私の主な弱点はファイル記述子にあります。pipe（int array [2]）は、stdinに対してarray[0] = fdを作成し、stdoutとしてarray[1]を作成することを理解しています。しかし、これら2つの間のこのコミュニケーションはどうですか？私はCSにかなり慣れていません。ありがとう！

/*
 * This program demonstrates the use of pipes for interprocess communication.
 * The parent process creates a pipe using the "pipe" system call. It then
 * creates a child process and passes the child a file descriptor for one side
 * of the pipe. It then writes a name to its side of the pipe and waits for the
 * child to print a message incorporating the name.
 *
 * Before you attempt to run this program, be sure you've compiled the program
 * named "hw3b.c" and have the executable in a file named "hw3b".
 */

#include <stdlib.h>
#include <strings.h>
#include <stdio.h>

/*
 * The name of the file we plan to run.  It's here in a define so that we can
 * change it easily
 */
#define CHILDPROCNAME "hw3b"

/*
 * The behavior of main() is specified by the previous comment
 */

int main(char* argv)
{
    // store the ids of the two file descriptors that serve as the pipe
    int mypipe[2];

    // make the pipe
    pipe(mypipe);

    // child code:
    if (fork() == 0) {
        // execv requires us to create a full invocation, consisting of the
        // string name of the program to run, a string for each command-line
        // argument, and then a null string.  We store all that in this array of
        // strings
        char* myargv[3];

        // we use this to turn an int into a string
        char buf[50];

        //  set up the name of the program to run
        myargv[0] = calloc(strlen(CHILDPROCNAME) + 1, sizeof(char));
        strcpy(myargv[0], CHILDPROCNAME);

        // write one of the pipe's fds to the second parameter
        sprintf(buf, "%d", mypipe[0]);
        myargv[1] = calloc(strlen(buf) + 1, sizeof(char));
        strcpy(myargv[1], buf);

        // third param is null
        myargv[2] = 0;

        // switch to child process
        execv(CHILDPROCNAME, myargv);

        // NB: this should use fprintf and write to stderr
        printf("Uh oh, execv didn't work!\n");

       // crash on failure
       exit(-1);
    }

    // parent code
    else {
       // status variable for storing the result of waitpid
       int status;

       // Send a string across the pipe to the child process
       write(mypipe[1], "Kerry", strlen("Kerry"));

       // wait for the child process to finish
       waitpid(-1, &status, 0);

       // NB: we should use status!
    }

    // close our half of the pipe
    close(mypipe[1]);
}
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1 に答える 1

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childprocプログラム内で。に置き換えるだけp1です。彼はそれが値に依存することを意味したかもしれませんp1。

于 2012-09-15T18:26:30.563 に答える